Boron trifluoride etherate → HCID 86737818, compound

Participants

Reaction Conditions

Reaction Steps

A solution of 11.7 g; 45 mmol of methyl 2,3,6-trideoxy-3-trifluroacetamido-α-L-ribohexopyranoside (V) in 100 ml of anhydrous methylene dichloride was treated at -70° C. with 0.6 ml of boron trifluoride etherate. While maintaining the temperature at -70° C., an excess of diazomethane in anhydrous methylene dichloride was added until a faint yellow color persisted. After 60 minutes at -70° C., a white solid (polymethylene) which precipitated out, was removed by filtration. The filtrate was washed successively with a 10% sodium bicarbonate solution and water, and then dried over anhydrous sodium sulphate. The filtrate was then evaporated to leave a residue, which was then chromatographed on a silica gel column. Elution of the column with chloroform gave pure methyl 4-O-methyl-2,3,6-trideoxy-3-trifluoroacetamido-α-L-ribohexopyranoside (VI) as an amorphous solid; m.p. 55°-60° C; [α]D23° =-110° (c=0.5 in CHCl3); mass spectrum: m/e 271 (M+). The p.m.r. spectrum showed absorption at: 1.30 (d, CH3 --C--5), 2.95 (dd, J=9.5 and 4.0 Hz, C--4--H), 3.42 and 3.43 (s,2 CH3O--), 3.70 (dq, J=6.0 and 9.0 Hz, C--5--H), 4.45-4.85 (m, C--3--H) and 4.75 δ (broad s WH =5.5 Hz, C--1--H).

Provenance & Evidence